A Tempting Terrorist Target

While a great deal of attention has been justifiably paid to airline security threats in light of the attacks of 9/11, there remains another threat, one that is more widespread and potentially more lethal: toxic industrial chemicals (TICs).

Homeland security and homeland defense organizations are focusing on chemicals as potential weapons of mass destruction, and have made a chilling discovery: there exists an increasing likelihood that the vast amount of industrial chemical sources throughout the United States could be exploited for terrorist actions.

In light of the prevalence of toxic industrial chemicals, it is necessary to develop technology strategies that assist human monitoring activities.

The Threat is Global

In 2002, the Pittsburgh Tribune-Review reviewed the region's trains, trucks and tugs and discovered that thousands of rail cars loaded with hazardous chemicals were left unprotected and parked in populated areas, near houses, retirement homes, schools and day care centers. Federal law permits them to park for up to two days in most cases.

For over 40 years, the Anniston U.S. Army Depot in Anniston, Ala., has stored over 2,200 tons of Cold War-era chemical weapons in earth-covered, concrete-reinforced bunkers. Since August 2003, the Army has destroyed over 18,000 rockets and 20,000 gallons of liquid GB, better known as sarin. More than 70,000 people live within nine miles of the incinerator, and since February 2004 there have been two alarms indicating leakage of sarin into the environment.

Each day, liquids and gases used in U.S. manufacturing course through 2.1 million miles of pipelines. Approximately 800,000 to 1.2 million loads of hazardous materials are transported around the country across more than 200,000 miles of track, highways and inland waterways.

The Threat is Widespread and Easy to Access
The focus on chemicals such as sarin used as a weapon of mass destruction (WMD) is important, but the threat from readily available industrial chemicals may be much greater. In a report to the U.S. Congress in 2002, the Central Intelligence Agency stated that terrorist groups "are most interested in chemicals such as cyanide salts to contaminate food and water supplies ... terrorists also have expressed interest in many other toxic industrial chemicals, most of which are relatively easy to acquire and handle ... such as traditional chemical agents, including chlorine and phosgene."

Chlorine is widely used in water purification, bleaches, crop protection solutions and in manufacturing a variety of organic compounds. Phosgene is used in the manufacturing of dyes, pesticides and plastics. Both chemicals can be considered choking agents, and since chlorine has an odor threshold that is lower than its toxicity threshold, victims may have some warning that there is a problem. Phosgene, however, has a toxicity threshold that is much lower than its odor threshold. In other words, inhalation of a lethal phosgene dose occurs well before any odor is detected.

The report fails to include another highly toxic substance that is even more widely used than chlorine and phosgene: ammonia. Ammonia is highly corrosive to the skin and eyes and can violently fume when exposed to water. 80 percent of the ammonia use in the United States is in agriculture, with the remaining 20 percent distributed across industries such as pulp and paper, metal treating, petrochemical, industrial refrigeration and food and beverage processing.

Chlorine, phosgene and ammonia -- in addition to many other TICs -- are widely used and have the potential to harm millions of people. In 2001, a Washington Post article noted an industrial plant in New Jersey that contained enough chlorine to create a cloud that could endanger over 12 million people.

Responding to the Threat
The threat we face is asymmetrical. That is, it can happen anywhere at any time. It is a threat that is not announced, and it is most often undertaken by well-organized groups of radically ideologically similar people.

Terrorists will choose the softest available target to achieve their ends, whether that is to destroy a symbolic target, an economic target, a public infrastructure target or a political target. In some cases, as recently happened in Spain, the toll taken on commuter railways affected a national election. The reality is that industrial chemicals present a tempting, relatively unprotected source of materials for a terrorist attack.

Vigilance and protection of industrial targets needs to be increased, but the problem is clear: there are simply not enough people to ensure adequate levels of around-the-clock protection at every conceivable target. From chemical manufacturing and processing to water treatment, rail lines and ports, the targets are simply too numerous.

Adding to the fact that people are not cost-effectively scalable to cover the threat, the ones that are on the front lines of protection must be adequately equipped to protect property, themselves and to provide community awareness and protection of the public at large.

Powerful handheld sensors and wireless sensing networks are already being deployed at many industrial, public venue and transportation sites, providing a critical safety net. Some monitors are able to detect concentrations of volatile organic compounds (VOC) such as chlorine, phosgene and ammonia in the parts-per-billion range, and in this way are providing an effective early warning system to workers and first responders. Fixed and wireless sensing networks are putting nodes of monitors around fence lines and security checkpoints at sites such as nuclear power plants, offshore oil platforms and at a variety of public venues such as arenas and subways.

Broad-spectrum handheld VOC monitors and networked solutions are using photoionization detection (PID) and other technologies to provide instant detection of hundreds of life-threatening VOCs. For now, these methods are proving an effective deterrent in conjunction with other security measures. In a hazardous situation when every second counts, the speciation of a specific toxic chemical is second to having the threat information to make a quick "go/no go" decision.

As powerful as they are, though, these local networks and handheld monitors will ultimately be joined by something far more powerful: pervasive sensing.

Pervasive Sensing
It's useful to compare the potential of pervasive sensing to the rise of the Internet. When personal computers were first sold, their use was local. Users could use many helpful applications, and this was a breakthrough in many ways. However, the true potential became apparent when the Internet made it possible to access unlimited content and communicate it with others.

The one-person-one-monitor approach will always play an important role in hazardous environment detection (such as in wing tank entry and confined space applications), but the true potential of environmental monitoring lies in the ability to deploy millions of tiny sensors and interconnect them using wireless or Internet technologies for a complete, real-time picture of environmental threats.

In fact, as this happens, the focus will shift from the monitoring itself to the analysis, interpretation and decision support related to the data. Mesh networks are a good example of how this is now being rolled out. A wireless mesh network is a "multihop" system, which means that devices assist each other in transmitting packets through the network, especially in adverse conditions. Wireless mesh networks use routing algorithms to create extremely resilient, self-organizing and self-healing networks, with very low power requirements and no single point of failure. These networks automatically route traffic around the typical interference found in difficult radio conditions, and with increased flexibility in deployment, maintenance and operation, the networks can be extended to thousands of sensors.

Not only could networks of wireless sensors be used to track hazardous shipments, but sensors could be deployed in subways, arenas, buildings, homes and even automobiles, promising to provide instant and real-time updates of the onset and dissemination of toxic plumes and chemicals.

Pervasive sensing networks could be deployed in water treatment systems, from the main facility to branches throughout the networks, showing where a threat has been released and where it is moving. Buildings, factories and manufacturing facilities could be retrofitted at a fraction of the cost of wired sensors, providing security and air quality data to millions of workers.

We are at the beginning of a transformation in environmental monitoring. Wireless, integrated sensing networks will play an increasing role in keeping people safe, economic assets in production and symbolic targets protected. In addition to their life-saving capabilities, the role of these pervasive early warning systems makes sound economic sense.

More data, faster data and better data. Data is the driving force to counter the asymmetrical threat from people who might misuse toxic industrial chemicals. With pervasive sensing, critical decisions can be made faster, mitigating the loss of life and lessening the economic damage that a terrorist event or industrial accident causes.

This article originally appeared in the 05/01/2004 issue of Environmental Protection.